The strain concerns doctors because typical antibiotics don't seem to stop the disease.

"In our world, where we have lots of bacteria and lots of use of antibiotics," said Dr. Robert Genzel, an emergency room physician at Texas Health Harris Methodist Fort Worth hospital. "Just like we evolve, the bacteria evolve, and so you start seeing bacteria get selected out."

The scare started in California, Oregon and Washington. But illnesses have now spread to a total of 18 states, including Texas.

Preventing the spread of the bacteria is as simple as washing your hands and keeping counter tops and utensils clean.

"People have to remember that while you're cooking the chicken, chopping it up, don't be testing the salad at the same time," Genzel said.